Two similar words both lie within a line; what follows?

Radd al-ʿAjz ʿalā al-Ṣadr: Repetition, Paronomasia and Derivation in Prose and Poetry

• It must be radd al-ʿajz
• Jinās is possible, but required ending is unverified
• It must be antithesis
• It is certainly derivation